Ivana Pavlinac Dodig, M.D., Ph.D.

1 2 1. Brainstem 1. Medulla oblongata 2. Pons 3. Mesencephalon 2. Cranial nerves 3. Cerebellum

3 4 5 Connecting spinal cord to cerebrum and cerebellum. Suprasegmental region of CNS.

ƒ Medulla oblongata ƒ Pons ƒ Mesencephalon

6 ƒ Grey matter continuity – from spinal cord via brainstem tegmentum to diencephalon

ƒ White matter continuity – long ascending and descending fibers

7 Physiological roles: ƒ Regulation of breathing ƒ Regulation of cardiovascular system ƒ Regulation of gastro‐intestinal system ƒ Regulation of movements ƒ Regulation of body balance ƒ Regulaation of eyes movements

8 1. Ventral or basal part (basis) = motor pathways 2. Middle part or tegmentum = sensory pathways, reticular formation, cranial nerve nuclei 3. Dorsal part or tectum – only in midbrain; visual and auditory system

9 ƒ Long descending motor pathways: ƒ Corticospinal ƒ Corticobulbar ƒ Corticopontine

10 ƒ Cranial nerves nuclei ƒ Reticular formation ƒ Big extrapyramidal motor nuclei (nucl. ruber and substantia nigra) ƒ Special monoaminergic tegmental nuclei (nucl. raphe, VTA, locus coeruleus)

11 ƒ Sensory: lemniscus medialis, tractus spinothalamicus and trigeminothalamicus ƒ Extrapyramidal ƒ Non‐specific ascendent pathways (serotoninergic, noradrenergic and cholinergic)

12 ƒ 50 nuclei ƒ Paramedial area – raphe + reticul. nuclei ƒ Medial area ƒ Lateral area ƒ Physiological roles: ƒ Modulation of sensory transmission to the cortex ƒ Regulation of motor activity ƒ Autonomic regulation ƒ Sleep and wakefulness cycle ƒ Modulation of emotional behaviour

13 14 ƒ Reticular nuclei of the pons – excitation of the antigravity muscles ƒ Medullary reticular nuclei – inhibition of the antigravity muscles antagonistic action

15 ƒ Rostral third = open medulla ƒ Caudal 2/3 = closed medulla ƒ Dorsal surface of tegmentum = bottom of IV. ventricle ƒ Lissauer’s zone = tractus spinalis n. trigemini

ƒ Pyramids = corticospinal tract; decussation ƒ Olives = inferior olivary nucl. ƒ Nucl. gracilis and cuneatus

16 ƒ Major fiber tracts ƒ Internal nuclei

17 ƒ Tegmentum = extrapyramidal motor and sensory pathways (lemniscus medialis, tractus spinothalamicus*, spinotectalis, spinoreticularis* and spinocerebellaris) and RF ƒ FLM (connecting vestibul. nuclei and lower motor neurons)

* lemniscus spinalis

18 ƒ Tractus corticospinalis ƒ Tractus tectospinalis ƒ Tractus rubrospinalis ƒ motor Tractus reticulospinalis lat. and med. ƒ Fasciculus longitudinalis medialis ▪ Descending part (medial vestibulospinal tract) ▪ Ascending part (from medial, lateral, and superior vestibular nuclei to pons and midbrain; information about head position to cranial nerves) ƒ Lemniscus medialis ƒ Tractus spinalis n. trigemini – somatosensory information from the head (Neuron II) sensory ƒ Tractus spinothalamicus ƒ Tractus spinocerebellaris 19 ƒ Reticular formation ƒ Nucl. gracilis and cuneatus ƒ Inferior olivary nuclei (spino‐olivary and rubro‐olivary fibers; to cerebellum) ƒ Nucl. spinalis n. trigemini (pain and temperature from head) ƒ Cochlear nuclei (n.VIII) ƒ Vestibular nuclei (n.VIII) ƒ Hypoglossal nucl. (n.XII) ƒ Nucl. ambiguus (n.IX & X) ƒ Nucl. tractus solitarii (n.IX & X) ƒ Dorsal motor vagal nucl. (n.X)

20 1. Level of pyramidal decussation 2. Level of medial lemniscus decussation (+accessory cuneate nucl. –external arcuate fibers – cuneocerebellar tract –inferior cerebellar peduncle: unconscious proprioception from upper limbs) 3. Rostral half of medulla – cranial nerve nuclei

21 ƒ General somatic efferent neurons (GSE) ƒ Special visceral efferent neurons (SVE) ƒ General visceral efferent neurons (GVE) ƒ General visceral afferent neurons (GVA) ƒ Special visceral afferent neurons (SVA) ƒ General sensory afferent neurons (GSA) ƒ Special sensory afferent neurons (SSA)

22 ƒ GSE – hypoglossal nucl. ƒ SVE –nucl. ambiguus (IX, X) ƒ GVE – parasympathetic (dorsal motor vagal nucl., nucl. salivatorius inferior) ƒ GVA – solitary nucl. (IX, X) – cardiovascular and respiratory reflexes ƒ SVA – gustatory portion of the solitary nucl. (taste) ƒ GSA –spinal nucl. of trigeminal nerve ƒ SSA – vestibular and cochlear nuclei

23 GSE – SVE – GVE – GVA & SVA – GSA – SSA

GSE

GVE GVA & SVA SSA

GSA

SVE

24 Lateral medullary syndrome (Wallenberg’s) ƒ Contralateral body and ipsilateral face loss of pain and temperature (spinothalamic and spinal trigeminal tract), loss of gag reflex, hoarseness, difficulty with speech and swallowing (nucl. ambiguus) ƒ Horner’s syndrome = loss of sympathetic functions Medial medullary syndrome (Dejerine’s) ƒ Pyramid, medial lemniscus and root fibers of n. XII Dorsal medullary syndrome ƒ Inf. cerebellar peduncle (ataxia), vestibular nuclei (nystagmus, vomiting, vertigo) 25 ƒ Basis: ƒ fibers ƒ nuclei ƒ Tegmentum: ƒ fibers ƒ nuclei

26 ƒ Fasciculi longitudinales ƒ corticospinal ƒ corticobulbar (corticonuclear) interneurons of RF ƒ corticopontine ƒ Transverse pontine fibers (pontocerebellar) ƒ Nuclei pontis (deep)

27 ƒ Fibers: ƒ fasciculus longitudinalis medialis ƒ lemniscus medialis ƒ spinothalamic and trigeminothalamic pathways ƒ lemniscus lateralis (auditory pathway) ƒ extrapyramidal pathways ƒ tractus rubrospinalis ƒ tractus tectospinalis

28 ƒ Nuclei pontis: ƒ RF (including raphe nuclei), ƒ auditory relay structures: corpus trapeziodeum, superior olivary nucleus (from cochlear nuclei) ƒ nucleus locus coerulei, ƒ cranial nerves nuclei (V, VI, VII, superior and lateral vestibular nuclei)

29 ƒ The locked‐in syndrome ƒ large infarct of the basilar pons – corticobulbar and corticospinal tracts ƒ communication by blinking and moving eyes

30 ƒ Tectum (corpora quadrigemina) ƒ Tegmentum ƒ Basis (crus cerebri)

31 ƒ Colliculi inferiores (auditory relay component; fibers of lemniscus lateralis from cochlear, sup.olivary nucl., and trapeziod body; to CGM – brachium of the inf. colliculus)

ƒ Colliculi superiores (inputs from retina; projects to cervical spinal cord via tectospinal tract)

32 ƒ PAG (enkephalin‐modulation of pain; regulation of autonomic, affective and emotional functions) ƒ Cranial nerves nuclei (III,IV+MLF) ƒ L&M lemniscus, spinothalamic, trigeminothalamic pathways ƒ RF (including raphe – somatomotor, autonomic and visceral regulation) ƒ Decussation of the superior cerebellar peduncle ƒ Substantia nigra ƒ Nucleus ruber (rostral half, motor functions) ƒ VTA –dopaminergic mezocortical system

33 ƒ Pretectal area (pupillary light reflex)

ƒ Posterior commissure (pretectal area – coodination of eyes’ movements)

ƒ Thalamic structures (pulvinar, medial and lateral geniculate nuclei)

34 35 36 ƒ Sensory: ƒ I. ƒ II. ƒ VIII. ƒ Motor: ƒ IV. ƒ VI. ƒ XI. ƒ XII

37 ƒ Genereal somatic efferents (GSE): ƒ CN III, IV, VI, XII ƒ skeletal muscles derived from somites ƒ Special visceral efferents (SVE): ƒ CN V, VII, IX, X, XI ƒ skeletal muscles derived from branchial arches ƒ General visceral efferents (GVE = autonomic): ƒ CN III, VII, IX, X ƒ smooth muscles and glands

38 Precentral gyrus Capsula interna Brainstem (area 4*) Tractus corticobulbaris

Neuron I (upper motoneuron) Neuron II Cranial nerves’ (lower nuclei motoneuron)

n. III, IV, V, VI, VII, IX, X, XI, XII

39 ƒ General somatic afferents (GSA) ƒ CN V, VII, IX, X ƒ sensations of pain, temp, touch, pressure ƒ Special sensory afferents (SSA) ƒ CN II, VIII ƒ From highly specialized somatic receptors ƒ Special visceral afferents (SVA) ƒ CN I (olfaction), CN VII, IX, X (taste) – chemoreceptors ƒ General visceral afferents (GVA) ƒ CN IX and X (visceral pain, chemoreception, general unpleasent feelings)

40 SSA GSA SVA+GVA GSE SVE GVE 41 42 ƒ SVA (receptors are chemoreceptors) ƒ Enters the brain through the cribriform plate and supplies the olfactory bulb

43 ƒ SSA

ƒ Conveys visual signals to the CNS

ƒ Enters the brain at the level of the preoptic region of the diencephalon

44 ƒ GSE – extraocular eye muscles

ƒ GVE – parasympathetic inervation of the pupillary and ciliary muscles

45 Motor nucleus: ƒ situated in the mesencephalon (level of the superior colliculus) – fossa interpeduncularis – the orbit ƒ Superior, medial, and inferior rectus musles, inferior oblique and levator palpebrae superior muscle

ƒ Bilateral corticobulbar inervation

46 Westphal –Edinger nucleus ¾ Most of the fibers: ciliary ganglion (m. constrictor pupillae*) ¾ Some fibers pass through ciliary ganglion and synapse in episcleral ganglion – ciliary muscle (accomodation)

* M. dilatator pupillae –sympathetic fibers from superior cervical gangl.

47 ƒ GSE ƒ M. obliquus superior – moves eye downward while in medial position

48 ƒ SVE (muscles of mastication; upper motoneuron = bilateral inputs from the cortex; lower motoneuron lesions – difficulties in chewing and biting responses)

ƒ GSA (somatosensory inputs from the anterior 2/3 of the head)

49 ƒ GSA from the anterior 2/3 of the head ƒ Three principal divisions: ƒ Ophtalmic ƒ Maxillary ƒ Mandibular

50 Neuron I Neuron II

Ganglion Trigeminal Skin receptors semilunare Tractus spinalis n.V. nerve Gasseri

Ventral trigeminothal.tract

Postcentral gyrus VPM of the Internal capsule (area 3,1,2) thalamus

Neuron III

51 Neuron I Neuron II

Ganglion Main sensory nucl. Of Skin receptors semilunare n.V. (pons) Gasseri

Dorsal Ventral trigeminothal. trigeminothal. tract tract

Postcentral VPM of the Internal capsule gyrus (area 3,1,2) thalamus

Neuron III

52 ƒ Muscle spindles in masticatory muscles and temporomandibular joint –via mandibular branch ƒ Neuron I = mesencephlic nuceus

53 Trigeminal neuralgia (tic douloureux) ƒ Often localized to a portion of one side of the face (associated with a specific branch) ƒ Unknown etiology (irritation of the trigeminal nerve by inflammation, tumor, or vascular lesion) ƒ Therapy? Surgery?

54 ƒ GSE ƒ M. rectus lateralis – moves eye laterally ƒ Clinical disorder: medial strabismus

55 ƒ Motor components: ƒ SVE (muscles derived from the second branchial arch) ƒ GVE (parasympathetic: salivation, lacrimation, nasal cavity mucosal secretion) ƒ Sensory components: ƒ GSA (somesthetic impulses from the back of the ear and external auditroy meatus) ƒ SVA (taste)

56 ƒ SVE ƒ Muscles of facial expression, auricular, posterior belly of digastric , styloyoid, platysma and stapedius muscle

ƒ GVE ‐ parasympathetic inervation ƒ from the superior salivatory nucl. to the submandibular (submandibular and sublingual glands) and pterygopalatine ganlion (lacrimal, nasal and palatine glands)

57 ƒ SVA – taste from the anterior 2/3 of the tongue – geniculate ganglion – solitary nucl. – thalamic VPM nucl. ƒ GSA –back of the ear and external auditory meatus – geniculate ganglion – spinal tract of the trigeminal nucl. ƒ Pain and temp, pressure, tactile stimuli

58 ƒ Upper part of the face = bilateral inervation ƒ Lower part of the face = contralateral inervation

59 ƒ SSA ƒ Auditory and vestibular signals for the CNS

60 ƒ Motor components: ƒ SVE (muscles derived from the branchial arches) ƒ GVE (salivation) ƒ Sensory components: ƒ GSA (somesthetic impulses from the back of the ear) ƒ GVA (changes of the blood pressure) ƒ SVA (taste and blood oxygen level)

61 ƒ SVE –from the nucl. ambiguus ƒ M. stylopharyngeus – speech and swallowing

ƒ GVE –from the inferior salivatory nucl. to the otic ganglion ƒ Parasympathetic inervation of the parotid gland ‐ salivaton

62 ƒ GVA – baroreceptors in carotid sinus – inferior (petrosal) ganglion – solitary nucl. ƒ Carotid sinus baroreflex ƒ GSA – tympanic membrane and skin of the external ear, posterior third of the tongue, eustachian tube, tonsil and upper part of the pharynx – superior ganglion – spinal trigeminal nucl. ƒ Pain and temp, pressure, tactile stimuli

63 ƒ SVA ƒ Respiratory functions: chemoreceptors (PaO2, PaCO2, pH of the blood) in the carotid body – inferior ganglion – solitary nucleus, RF ▪ Carotid body chemoreflex ƒ Taste functions: taste buds in posterior third of the tongue –inferior ganglion – solitary nucl. – VPM thalamic nucl.

64 ƒ Motor components: ƒ SVE (muscles derived from the branchial arches) ƒ GVE (body viscera) ƒ Sensory components: ƒ GSA (somesthetic impulses from the back of the ear) ƒ GVA (changes of the blood pressure) ƒ SVA (taste and blood oxygen level)

65 ƒ SVE –from the nucl. ambiguus ƒ Muscles of the pharynx and larynx – role in speech

ƒ GVE –from the dorsal motor nucl. ƒ Parasympathetic inervation of the body viscera to left colic flexure ƒ Bronchoconstriction, speeding up of peristalsis, cardiac cycle slowing, increases in bronchi, stomach, pancreas and intestines’ secretion

66 ƒ GVA –body viscera and aortic arch –inferior (nodose) ganglion – solitary nucl. ƒ Unconscious (baroreceptors in aortic arch, part of baroreceptor reflex) and conscious (thirst, hunger) sensory inputs from the viscera ƒ GSA –back of the ear and external auditory canal – superior (jugular) ganglion – spinal trigeminal nucl. ƒ Pain and temp, pressure, tactile stimuli

67 ƒ SVA ƒ Respiratory functions: chemoreceptors (PaO2, PaCO2, pH of the blood) in the aortic body – inferior ganglion – reticular formation ƒ Taste functions: taste buds in epiglottis and posterior pharynx wall –inferior ganglion – solitary nucl. –VPM thalamic nucl.

68 ƒ SVE / GSE ƒ Ventral horn cells of first 5‐ 6 cervical segments ƒ M. trapezius and sternocleidomastoideus ƒ Contralateral turning and lifting of the head ƒ Supranuclear paralysis = contralateral

69 ƒ GSE ƒ Control of the shape and position of the tongue ƒ Extrinsic (styloglossus, hyoglossus, genioglossus) and intrinsic muscles of the tongue ƒ Damage –protruded tongue deviates to the side of the lesion ƒ Contralateral inervation! 70 Brainstem Nerve Nucleus Ganglion location N. oculomotorius Westphal‐Edingerova Ciliary Mesencephalon Submandibulary N. facialis Nucl. salivatorius sup. Pons Pterygopalatine N. glossopharyngeus Nucl. salivatorius inf. Oticum M. oblongata

N. vagus Nucl. dorsalis n. vagi At visceral organs M. oblongata

71 ƒ Integration of information from spinocerebellar pathways, vestibular nuclei and cortex (via pons and cerebellar peduncles) ƒ Cortex, white matter, deep nuclei ƒ Two hemispheres + vermis ƒ Main neurotransmitter: GABA

72 ƒ Attached to the brainstem by: ƒ Inferior cerebellar peduncle –fibers from spinal cord and lower brainstem regions

afferent ƒ Middle cerebellar peduncle –cortex –pons –cortex cerebelli ƒ Superior cerebellar peduncle –to nucl. ruber and VLN of

efferent thalamus

73 ƒ Folia; no gyri and sulci ƒ 3 layers of the cells: ƒ Purkinje cells layer ƒ Molecular layer ƒ Granule cell layer

74 ƒ Nucleus fastigii (=nucl.medialis) –to RF and vestibular neurons ƒ Nucleus globosus = nucl.interpositus –to nucl. ruber ƒ Nucleus emboliformis ƒ Nucleus dentatus (=nucl.lateralis) –to VLN of thalamus

75 Anatomical name Filogenetic name Functional name

Lobus anterior Paleocerebellum Spinocerebellum

Pontocerebellum / Lobus posterior Neocerebellum Cerebrocerebellum

Lobus flocculonodularis Archicerebellum vestibulocerebellum

76 77 ƒ Loss of balance ƒ Tremors ƒ Lack of coordination of muscles ƒ Reduced muscle tone

78